Torsion bar control for executive posture chair

ABSTRACT

A torsion bar control for an executive posture chair wherein chair seat support structure is mounted for pivotal movement about a first horizontal axis, and chair back support structure is pivotal about a second horizontal axis defined by a torsion bar. The seat support and back support structures are connected to one another at a location spaced from the above-mentioned pivotal axes for limited movement relative to one another.

United States Patent Inventor James R. Meinhardt Park Ridge, Ill.

App]. No. 573,089

Filed Aug. 17, 1966 Patented Oct. 12, 1971 Assignee The Seng Company.

TORSION BAR CONTROL FOR EXECUTIVE POSTURE CHAIR 4 Claims, 8 Drawing Figs.

US. Cl 297/303 Int. Cl A47c 3/00 Field of Search 297/300 [56] References Cited UNITED STATES PATENTS 2,441,251 5/1948 Raitch 297/316 2,498,106 2/ 1950 Elleman 297/301 Primary Examiner-Bobby R. Gay Assistant Examiner-Glenn O. Finch Atlorney-Hofgren, Wegner, Allen, Stellman & McCord ABSTRACT: A torsion bar control for an executive posture chair wherein chair seat support structure is mounted for pivotal movement about a first horizontal axis, and chair back support structure is pivotal about a second horizontal axis defined by a torsion bar. The seat support and back support structures are connected to one another at a location spaced from the above-mentioned pivotal axes for limited movement relative to one another.

PATENIEoum 12 I97! SHEET 10F 3 INVEN TOR JA MES R. ME/NHARDT ATTYS.

PAIENIEunm 12 Ian sum 2 or 3 TORSION BAR CONTROL FOR EXECUTIVE POSTURE CHAIR This invention relates to an executive posture chair, and in particular it relates to such a chair in which the back and seat are resiliently urged to their unoccupied positions by a single torsion bar.

Executive posture chairs are those in which there is a differential inclination of the seat and back, so thatas the seat tilts the back is inclined more than the seat.

Torsion bar chair controls are increasingly popular because they permit a very compact, simple, and dependable structure but prior to the present invention they had been applied to executive posture chairs only by using one torsion bar for the seat and a second for the back, as in Lie U.S. Pat. No. 2,991,125.

In accordance with the present invention, a single torsion bar controls the tilting movement of a back support structure which pivots about the longitudinal axis of the torsion bar, and the seat is pivoted directly on a stationary chair base by means of a seat support structure in the form of arms which are connected to the back support structure by links which permit limited related movements of the seat and back.

The invention is illustrated in a preferred embodiment in the accompanying drawings in which:

FIG. I is a side elevational view of an executive posture chair constructed in accordance with the present invention;

FIG. 2 is a longitudinal sectional view on an enlarged scale, taken substantially as indicated along the line 2-2 of FIG. 4; with the seat and back in upright position;

FIG. 2a is a fragmentary side elevational view on the scale of FIG. 2 with the seat and back bracket in tilted position;

FIG. 3 is a fragmentary transverse sectional view taken substantially as indicated along the line 33 of FIG. 2;

FIG. 4 is a fragmentary front elevational view taken substantially as indicated along the line 4-4 of FIG. 3;

FIG. 5 is a transverse sectional view on an enlarged scale, taken substantially as indicated along the line 5-5 of FIG. 2;

FIG. 6 is a fragmentary view like FIG. 2A with the parts in upright position; and

FIG. 7 is a fragmentary longitudinal sectional view taken substantially as indicated along the line 7-7 of FIG. 5.

Referring to the drawings in greater detail, and referring first to FIGS. 1 and 2A, an executive posture chair includes a pedestal I0 having a hub 11; a chair iron, indicated generally at 12 which includes a threaded spindle l3, surmounted by a stationary support structure, or base 14, a torsion bar assembly indicated generally at 15, a back support structure, in-

dicated generally at 16 which pivots about the axis of the torsion bar assembly, and a seat support structure in the form of mounting arms 17 which are pivoted on the base at 18 and connected to the back support structure for limited related movements by links 19. An upholstered seat 20 is bolted to the mounting arms 17 and carries fixed arms 21, and a back 22 is secured to the back support structure 16.

Referring now particularly to FIGS. 2 and 5, the base 14 has a crossmember 23 with perpendicular arms 24 and 24a at opposite ends, and said arms have aligned holes 25 and 25a, respectively, to receive the torsion bar assembly 15. The base 14 also has an inclined transverse front portion 26 and a generally upright rear plate 27 that is surmounted by a rubber stop shoe 28.

The torsion bar assembly includes a first cube 29 which extends through the hole 25, a second tube 30 which is journaled in a nylon bushing 31 in the hole 25a, and a nylon connector bushing 32 which includes a first projecting plug portion 320 extending into the open inner end 290 of the tube 29, a second projecting plug portion 32b extending into the open inner end 30a of the tube 30, and a flange portion between said ends 29a and 30a. A plug 29b in the outer end of tube 29 and a plug 30b in the outer end of tube 30 have square holes to receive a square torsion bar 33 which passes through a square hole in the connector bushing 32, and ends 330 and 33b of the torsion bar 33 project, respectively, out of the plugs 29b and 30 b to receive friction caps 34 and 35. A crenate washer 36 engages the tube 30 and bears upon an external flange 31a of the bushing 31.

The back support structure 16 includes a channel bracket 37 having side webs 38 which embrace the tube 30 and are welded thereto, and the webs 38 have forward extensions 38a which seat on the crossmember 23 of the base 14 in the unoccupied position of the chair. Rearward extensions 38b of said webs 38 carry adjusting members 39 of conventional structure by means of which the height and tilt of the back 22 may be varied with respect to the structure 16.

As best seen in FIGS. 2 and 3, the links 19 which connect the seat arms 17 to the back support structure 16 are generally in the form of skewed channel members each of which has a flange 19a which is pivotally connected to a seat arm 17 by a loose rivet 17a a connecting web, and a flange 19b which is pivotally connected to a back bracket web 38 by a loose rivet 38c. Thus, the back support structure 16 and the seat support structure 17 are connected to each other at a moving pivot axis which is afforded by the links 19 and their pivots 17a and 380, and are thereby interconnected for limited related movements. As best seen in FIGS. 2A and 7, the seat arms 17 have large holes 17b through which the torsion assembly 15 extends so the brackets may pivot freely about their pivots 18 without interference from the torsion assembly.

As is customary for office swivel chairs, the present structure includes means for preloading the torsion bar to adjust the force by which it resists tilting of the back and the seat. In the present structure this includes a lever 40 in the form of a channel member which is secured to the tube 29, a threaded T-bolt 41 which hangs in an opening 400 in the channel member and extends through a hole in the front wall 26 of the base, and a handwheel capnut 42 which screws onto the free end of the T-bolt and bears on the wall 26 so that tightening the capnut on the bolt pulls down the lever 40. Since the end 33a of the torsion bar is fixedin the tube 29 which in turn is rotated by movement of the adjusting lever 40, while the end 33b of the torsion bar is fixed in the tube 30 which in turn is prevented from rotating clockwise as seen in FIG. 2 by the front extension 38a of the back bracket 16 on the base web 23, adjustment of the lever 40 by tightening the capnut 42 increases the preloading of the torsion bar. The torsion bar 33 is efi'ectively held against rotation in the base arm 24, because when the chair is in use the torsion bar occupies a fixed, nonrotatable position relative to said arm 24.

When an occupant of the chair presses against the back 22 to tilt the chair, the torsion bar 33 resists the tilting movement of the back and also of the seat in accordance with its preloading. The back support structure pivots about the axis of the torsion bar 33 from the position of FIGS. 2 and 6 to the position of FIG. 2A, and at the same time the seat arms 17 tilt about their pivots 18 as seen in those views, with the necessary relative movement between the seat support structure 17 and the back support structure 16 being permitted by the links 19.

The foregoing detailed description is given for cleamess of understanding only and unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

I claim:

1. A control for an executive-type posture chair having a chair back and a chair seat, comprising in combination sta tionary support structure, seat support structure supported by the stationary support structure to pivot about a given pivot axis and adapted to support the chair seat, back support structure supported by the stationary support structure to pivot about a second pivot axis and adapted to support the chair back, means connecting the seat and back support structures to one another at a location spaced from both the first and second pivot axes to interconnect them for limited related movements, and a single torsion bar connected at one location to the stationary support structure and connected operatively at a spaced location to either of the pivoted support structures to bias them to a position corresponding generally to the unoccupied position of the chair.

2. A control for an executive-type posture chair having a chair seat and a chair back adapted to pivot relative to one another and relative to a stationary chair post, comprising a crossmember adapted to be connected to the chair post, seat support structure adapted to support the chair seat, means pivotally connecting the seat support structure to the crossmember to pivot the seat support structure about a first pivot axis, a back support structure adapted to support the chair back, means pivotally connecting the back support structure to the crossmember to pivot the back support structure about a second pivot axis spaced from the first pivot axis, means pivotally connecting the seat and back support structures to one another for pivotal movement about a third pivot axis spaced from both the first and second pivot axes, means permitting a slight change in the distance between any two of the pivotal axes to interconnect for related movements the seat and back support structures, and means including a single torsion bar connected at one location to the crossmember and connected operatively at a spaced location to either of the two pivoted support structures for biasing them resiliently to a forward tilt position relative to the crossmember corresponding to the unoccupied position of the chair.

3. A control for an executive-type posture chair having a chair seat and a chair back adapted to pivot relative to one another and relative to a stationary chair post, comprising a crossmember adapted to be connected to the chair post, seat support structure adapted to support the chair seat, means pivotally connecting the seat support structure to the crossmember to pivot the seat support structure relative to the crossmember about a first pivot axis, a back support structure adapted to support the chair back, means pivotally connecting the back support structure to the crossmember to pivot the back support structure relative to the crossmember about a second pivot axis spaced from the first pivot axis, means pivotally connecting the seat and back support structures to one another for pivotal movement relative to one another about a third pivot axis spaced from both the first and second pivot axes, means including at least one of the pivotal connecting means being movable to accommodate a slight movement of two of the pivot axes toward and away from one another to interconnect thereby for related movements relative to one another the seat and back support structures, and means including a single torsion bar connected at one of its ends to the crossmember and connected operatively at the other of its ends to either of the two pivoted support structures for biasing them resiliently to a forward tilt position relative to the crossmember corresponding to the unoccupied position of the chair and operable upon the chair seat or chair back being tilted to a rearward tilt position to be strained from its initial strained condition to an even greater strained condition for imposing a greater resilient bias to the forward tilt position.

4. A control for an executive-type posture chair having a chair seat and a chair back adapted to pivot relative to one another and relative to a stationary chair post, comprising a cross member adapted to be connected to the chair post, seat support structure adapted to support the chair seat, means pivotally connecting the seat support structure to the crossmember to pivot the seat support structure about a first pivot axis located forward of the chair post, a back support structure adapted to support the chair back, means pivotally con necting the back support structure to the crossmember to pivot the back support structure about a second pivot axis spaced rearwardly from the first pivot axis, means pivotally connecting the seat and back support structures to one another for pivotal movement about a third pivot axis spaced rearwardly from both the first and second pivot axes and rearward of the chair post, means to accommodate a slight movement of any'two of the pivot axes toward and away from one another to interconnect for related movements the seat and back support structures, and means including a single torsion bar connected operatively between the crossmember and either of the two pivoted support structures for biasing them resiliently to a forward tilt position corresponding to the unoccupied position of the chair. 

1. A control for an executive-type posture chair having a chair back and a chair seat, comprising in combination stationary support structure, seat support structure supported by the stationary support structure to pivot about a given pivot axis and adapted to support the chair seat, back support structure supported by the stationary support structure to pivot about a second pivot axis and adapted to support the chair back, means connecting the seat and back support structures to one another at a location spaced from both the first and second pivot axes to interconnect them for limited related movements, and a single torsion bar connected at one location to the stationary support structure and connected operatively at a spaced location to either of the pivoted support structures to bias them to a position corresponding generally to the unoccupied position of the chair.
 2. A control for an executive-type posture chair having a chair seat and a chair back adapted to pivot relative to one another and relative to a stationary chair post, comprising a crossmember adapted to be connected to the chair post, seat support structure adapted to support the chair seat, means pivotally connecting the seat support structure to the crossmember to pivot the seat support structure about a first pivot axis, a back support structure adapted to support the chair back, means pivotally connecting the back support structure to the crossmember to pivot the back support structure about a second pivot axis spaced from the first pivot axis, means pivotally connecting the seat and back support structures to one another for pivotal movement about a third pivot axis spaced from both the first and second pivot axes, means permitting a slight change in the distance between any two of the pivotal axes to interconnect for related movements the seat and back support structures, and means including a single torsion bar connected at one location to the crossmember and connected operatively at a spaced location to either of the two pivoted support structures for biasing them resiliently to a forward tilt position relative to the crossmember corresponding to the unoccupied position of the chair.
 3. A control for an executive-type posture chair having a chair seat and a chair back adapted to pivot relative to one another and relative to a stationary chair post, comprising a crossmember adapted to be connected to the chair post, seat support structure adapted to support the chair seat, means pivotally connecting the seat support structure to the crossmember to pivot the seat support structure relative to the crossmember about a first pivot axis, a back support structure adapted to support the chair back, means pivotally connecting the back support structure to the crossmember to pivot the back support structure relative to the crossmember about a second pivot axis spaced from the first pivot axis, means pivotally connecting the seat and back support structures to one another for pivotal movement relative to one another about a third pivot axis spaced from both the first and second pivot axes, means including at least one of the pivotal connecting means being movable to accommodate a slight movement of two of the pivot axes toward and away from one another to interconnect thereby for related movements relative to one another the seat and back support structures, and means including a single torsion bar conNected at one of its ends to the crossmember and connected operatively at the other of its ends to either of the two pivoted support structures for biasing them resiliently to a forward tilt position relative to the crossmember corresponding to the unoccupied position of the chair and operable upon the chair seat or chair back being tilted to a rearward tilt position to be strained from its initial strained condition to an even greater strained condition for imposing a greater resilient bias to the forward tilt position.
 4. A control for an executive-type posture chair having a chair seat and a chair back adapted to pivot relative to one another and relative to a stationary chair post, comprising a cross member adapted to be connected to the chair post, seat support structure adapted to support the chair seat, means pivotally connecting the seat support structure to the crossmember to pivot the seat support structure about a first pivot axis located forward of the chair post, a back support structure adapted to support the chair back, means pivotally connecting the back support structure to the crossmember to pivot the back support structure about a second pivot axis spaced rearwardly from the first pivot axis, means pivotally connecting the seat and back support structures to one another for pivotal movement about a third pivot axis spaced rearwardly from both the first and second pivot axes and rearward of the chair post, means to accommodate a slight movement of any two of the pivot axes toward and away from one another to interconnect for related movements the seat and back support structures, and means including a single torsion bar connected operatively between the crossmember and either of the two pivoted support structures for biasing them resiliently to a forward tilt position corresponding to the unoccupied position of the chair. 